1. Background of the Prior Art
This invention relates to locking and latching apparatus for emergency exit doors. More particularly, this invention relates to latching and locking apparatus for emergency exit doors wherein the apparatus includes structure for delaying transition of a latch or lock from a latched mode to an unlatched mode.
As explained in copending U.S. patent application Ser. No. 929,968 filed by Emanuel L. Logan on Aug. 1, 1978 and incorporated herein by reference, there is a need for a new type of emergency exit door latching and locking apparatus in which retraction of a latch bolt is delayed by loading the bolt with a hydraulic throttling system in which a liquid is throttled as the bolt is urged against the strike. The present invention is a modification of the arrangement disclosed in U.S. patent application Ser. No. 929,968 and falls within the scope thereof.
As indicated in U.S. patent application Ser. No. 929,968, there is an inherent conflict between safety and security even though these two concerns are interrelated. This conflict becoms readily apparent when one considers the problems encountered in trying to optimize the design of emergency exit doors. At least some doors of public buildings, such as schools, theaters, auditoriums, resturants, and the like must, by law, be equipped with latches or locks that can be readily opened from within the building should there be a fire or other emergency situation. These locks and latches pose a security problem since doors which can be readily opened from the inside of buildings allow people within the buildings to easily escape with stolen articles and allow people within the buildings to open the doors and admit anyone they wish to the buildings. In the minds of security people, in many instances security problems caused by easily openable emergency doors far outweigh the dangers of fire. Consequently, emergency door exits are frequently locked with chains and other devices. This is problably done because security problems arise with greater frequency than fires and must be dealt with on a day-to-day basis whereas fires occur infrequently and the dangers of fire are therefore ignored. If emergency exits are locked the results are often catastrophic when fires do occur and this causes fire departments great concern.
The approach taken by U.S. patent application Ser. No. 929,968 solves the aforediscussed problems and the present invention further discloses the concepts of that application so as to render those concepts even more commercially viable.